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C 13 («,a)C 13 cross sections at center-of-mass angles 54.7°, 107.9°, 142.6°, and 169.6° and C 13 (a,#)0 16 cross sections at 0° have been measured at a-particle energies from 2 to 3.5 MeV. From dispersion-theory analysis, a consistent set of J* and partial-width values has been obtained for eleven states of the compound nucleus O 17 with excitation energies between 8 and 9 MeV. I. INTRODUCTIONT HE C 13 (a,w)0 16 reaction has been extensively investigated 1-5 at a-particle bombarding energies below 5 MeV. Resonances from sharp energy states of the compound nucleus O 17 are observed. We have measured 6 the C 13 (a,a)C 13 differential elastic-scattering cross sections for a-particle bombarding energies from 2.0 to 3.5 MeV at center-of-mass angles 54.7, 107.9,142.6, and 169.6°. C ls (a,n)O u differential reaction cross sections at 0° were measured simultaneously. Elastic-scattering and reaction data were analyzed to determine the J T and the a-particle and neutron partial widths of the states of O 17 corresponding to the observed resonances.The range 2 to 3.5 MeV of a-particle bombarding energies corresponds to the range 7.9 to 9 MeV of excitation energies in the compound nucleus O 17 . Values of / and of neutron and a-particle partial widths for many of the states at these excitation energies were known from C 13 (a,w)0 16 differential cross sections 2-5 and from total cross sections of O 16 for neutrons. 2 -5 » 7 From interference terms in C 13 (a,w)0 16 angular distributions, 4 -5 relative parities of a number of states were known. To determine parities and to make complete determinations of J and partial-width values, C 13 -(a,a)C 13 and O u (n y n)O u elastic-scattering experiments are necessary. The parameters of two states at the low end of the energy interval have recently been determined from analysis of 0 16 (^,w)0 16 angular distributions. 8

The level structure of the nucleus Ca 41 has been studied by the Ca 40 ()Ca 41 reaction at an incident deuteron energy of 7.00 MeV. Angular distributions have been measured for 120 levels below an excitation energy of 6.83 MeV, and those levels showing forward-stripping angular distributions have been analyzed using the distorted-wave Born approximation. Results on excitation energies, captured-neutron orbital angular momenta, and transition strengths are given for these levels. The data were further analyzed in terms of the shell model, and the unperturbed single-particle level positions with their corresponding spectroscopic factors were determined. For the (I/7/2) single-particle level at E x -0.0 MeV, 5 = 1.0; (2p m ),E x = 2.07 MeV, 5=1.22; (2p 1/2 ), E*=4.13 MeV, 5=1.17; (l/ 5 / 2 ), E x = 5.50 MeV, 5 = 0.48; (lg m ), £ x^4 .98 MeV, 5 = 0.07; (2dm), E x >6.8 MeV, 5 = 0.15; and (3s 1/2 ), E x >6.8 MeV, 5 = 0.05. The possible role of (U3/2) and (251/2) shell-model hole states is also discussed. 4 L. L. Lee and J. P. Schiffer, Phys. Rev. Letters 12, 108 (1964).

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